I. Field of the Invention
The present invention relates generally to turbine engine constructions and, more particularly, to a diffuser assembly for a turbine engine for an integrated combustor and turbine nozzle system.
II. Description of the Prior Art
Turbine engines conventionally include a support housing in which a turbine shaft is rotatably journalled. A compressor is connected to the turbine shaft and provides compressed air into a combustor means having a combustion chamber. Fuel is introduced into the combustion chamber and, upon combustion, the resulting hot and expanding combustion products expand through a relatively stationary turbine nozzle and into a turbine expander which rotatably drives the turbine shaft.
Typically, the combustor means includes a combustor housing which is annular in shape and defines the interior combustion chamber and a further chamber between the outer periphery of the combustor housing and the turbine support housing. The compressed air from the turbine engine compressor is exhausted into this outer annular chamber and thereafter enters the combustion chamber through a swirl plate in the combustor housing and other openings between the outer annular chamber and the combustion chamber.
In these previously known turbine engine constructions, however, the diffuser assembly has not been well integrated with either the combustor or the turbine nozzle. This lack of integration in turn results in more adverse temperature profiles, and/or larger volume turbine engines and/or less efficient turbine engines than can be otherwise accomplished. The turbine nozzle and rotor must be designed to accommodate the maximum local expected temperature of the combustor exhaust gases even though the average or mean temperature of the combustor exhaust gases is substantially less. The maximum survival temperature of the turbine nozzle is, as a practical matter, limited so that the lack of uniformity of the combustor exhaust gas temperature unnecessarily limits the overall efficiency for the turbine engine.
In these previously known turbine engine constructions, the combustion products exhausting from the combustion chamber and through the turbine nozzle enter the turbine nozzle with substantially an axial velocity direction component. The turbine nozzle, typically comprising a plurality of radially extending and circumferentially spaced vanes between the support housing and the combustor housing, diverts or shapes this gas circumferentially so that the gas flow exiting from the turbine nozzle impinges upon the first turbine wheel of the expander at an angle designed for maximum turbine efficiency. the turbine nozzle thus undergoes a great deal of aerodynamic loading which, again, creates an operating limitation for the overall turbine engine. Moreover, the nozzle must be of an axial length sufficient to shape the fluid flow without excessive aerodynamic loading on the vanes which significantly increases the overall length of the turbine engine.